我如何将学生添加到花名册中（来自Java中的不同班级）？

Question

public class Student {
private String name;
private String iD;
private boolean tuitionPaid;
/**Constructor*/
public Student(String studentName, String studentID)
{
    name = studentName;
    iD = studentID; 
}
/**Getters and Setters are below*/
public String getStudentName()
{
    return name;
}
public void setStudentName(String studentName)
{
    name = studentName;
}
public String getStudentID()
{
    return iD;
}
public void setStudentID(String studentID)
{
    name = studentID;
}
/**The toString method below*/
public String toString()
{
    String message = name + iD;
    return message;
}
}

public class Course {
private String name;
private int maxSize;
private String[] roster;

public Course(String courseName, int courseMaxSize)
{
    name = courseName;
    maxSize = courseMaxSize;
}


/**Getters and Setters are below*/
public String getCourseName()
{
    return name;
}
public void setCourseName(String courseName)
{
    name = courseName;
}
public int getCourseMaxSize()
{
    return maxSize;
}
public void setCourseMaxSize(int courseMaxSize)
{
    maxSize = courseMaxSize;
}
public String[] getCourseRoster()
{
    return roster;
}
public void setCourseRoster(Student s)
{
    String[] courseRoster = {s.toString()};//intended to pass the student name and ID
        roster = courseRoster;             //to the instance data variable

}

/**The toString method is below*/
public String toString()
{
    String message = name + " course has a class size of " + maxSize;
    return message;
}


/**Three requested methods are below*/
public boolean addStudent(Student s)
{

    boolean atCapacity = false;
    if(roster.length>=5)
    {
        String courseRoster[] = {s.toString()};//intended to pass the formal parameter
        roster = courseRoster;                 //to store as an instance data
        atCapacity = false;

    }
    else
    {
        atCapacity = true;      
    }
    return atCapacity;
}
public boolean dropStudent(Student s)
{
    boolean dropStudent = true;
    for( int index=0; index<roster.length - 1; index++ )//Goes through the roster
    {                                                   
        if( roster[index] == s.getStudentID() )//If a student matches, they are
        {
            s.setStudentID(null);               //dropped a student from a course
            s.setStudentName(null);             //their existence should be null
            dropStudent = true;
        }
        else
        {
            dropStudent = false;
        }
    }   
    return dropStudent;
}
public void printRoster()
{

        if(roster.length == 0)//In case there is no one in the roster
        {
            System.out.println("There is no one in this roster.");//this message prints
        }
        else
        {
        System.out.println(roster);//Everyone in class will be printed
        }
}
}

public class Project2DriverProgram {

public static void main(String[] args) {

    Student[] students = new Student[5];//Creates an array of objects from the Student-class
    students[0] = new Student("Bill", "123");//Instantiates the array at 0 with actual parameters

    Course newCourse = new Course("Philosophy", 5);//Creates an object and instantiates


    newCourse.getCourseRoster();
    newCourse.setCourseRoster(students[0]); //Sets the student to be in the roster

    newCourse.addStudent(students[0]);//Adds student to the course 


    newCourse.printRoster();//prints values of the roster

}

}

Answer 1

您的代码中有一个逻辑错误：

if(roster.length>=5){
atCapacity = true; 
String[][] roster = {{s.getStudentName()}, {s.getStudentID()}};
}
else{
    atCapacity = false;
}//end of else statement

应更改为：

if(!(roster.length>=5)){
 String[][] roster = {{s.getStudentName()}, {s.getStudentID()}};
 atCapacity = false;
}
else{
  atCapacity = true;
}

相反，当前的代码读作“如果容量大于或等于5然后添加一个新条目”，而实际上您想说“如果容量不大于或等于5添加一个新条目”。